The invention relates to a distributor chute for bulk material, in particular for use in a bell-less blast furnace top charging device.
In bell-less blast furnace top charging devices the charging material falls in metered quantities from an intermediate hopper through a vertically arranged central feed channel onto a distributor chute. This distributor chute is arranged centrally in the blast furnace top, can be rotated about the vertical axis of the blast furnace and pivoted about a horizontal axis, to change its inclination. The charging material, which consists of ore, coke, iron sinter etc., is a very hard, sharp-edged bulk material, which makes great demands on the distributor chute. This abrasive bulk material first strikes the distributor chute with a considerable impact energy in an impact zone of the chute and then tumbles down a sliding zone of the chute at a high speed. It follows that the distributor chute is subjected to a high degree of wear and must be changed frequently, which involves high costs and necessitates bringing operation of the blast furnace to a standstill.
German patent specification DE-A-23 25 531 (corresponding to U.S. Pat. No. 3,889,791 discloses a distributor chute of a bell-less blast furnace top charging device which has an outer shell of heat-resisting steel and a lining of individual wearing plates detachably secured to the outer shell. These wearing plates are arranged like scales, partially covering each other so that, in the direction of flow of the material, the lower part of each plate protrudes with respect to its upper part. They consist of a carrier plate of a thick-walled heat-resisting steel plate. A layer of hard material resistant to abrasion is welded onto this carrier plate.
To further reduce the wear and tear of this wearing plates disclosed in DE-A-23 25 531, German patent specification DE-A-26 29 782 proposes welding a small retaining ridge perpendicularly onto the surface of the overlapping wearing plates. In practice, it has been found, that these welded-on retaining ridges are primarily effective in the sliding zone of the chute, in that they reduce the speed of the bulk material directly adjacent to the surface of the wearing plates. In the impact zone the wear reducing effect of the welded-on retaining ridges is however insignificant.
Further disadvantages of the known overlapping wearing plates are their detrimental effect on the concentration of the flow of bulk material in the sliding zone, their high manufacturing costs and the high weight of a distributor chute with overlapping wearing plates.